They could have laid a rope equaling the linear length of the circumference and tied knots in it equaling the amount of divisions needed, they could have found the chord length then transferred it to the circumference, we know they new PI and the golden ratio, geometry was a doddle to them.

The angle of the pyramids comes from sand falling from a bucket with a hole in it, and the base to height are equally proportional they were 2500 years before the Greeks, we know the Greeks new it all as the Romans stole there work.

To sum up... all you need to build a pyramid is a bucket with a hole in it, sand, a round wooden wheel (any diameter) 1.8 million tons of stone from a quarry 600 miles away from your building site and a unionized work force of 100,000 men working two shifts.